Officer Richard Haste has decided to quit the police force following a departmental trial related to Graham’s death.

The 35-year-old was found guilty of all charges on Friday — including using poor tactics — and had been told that Deputy Commissioner of Trials Rosemarie Maldonado was going to ask Police Commissioner James O’Neill to fire him.

“Officer Richard Haste decided to quit the NYPD upon being informed that on Friday March 24th the Department Trial Commissioner found him guilty on all counts and recommended his employment be terminated,” the NYPD said in a statement.

“Police Commissioner O’Neill has fully concurred with the findings and recommendations of the Trial Commissioner.”

The departmental hearing for Haste — who shot and killed the unarmed Graham, 18, on Feb. 2, 2012 after chasing him inside his Bronx apartment — concluded in January.

A Bronx grand jury had previously indicted the cop in Graham’s death in June 2012, but a judge chose to toss the case out after the assistant district attorney made a technical mistake before the trial. A second attempt to indict him later failed.

“He was exonerated by both a state and federal grand jury,” Haste’s lawyer, Stuart London, told the Associated Press.

“The New York City Police Department Firearms Discharge Review Board found the shooting to be justified,” he said. “All of officer Haste’s actions were performed in good faith. He never should have been forced to resign based on tactics alone.”

Sources told The Post that Haste initially planned on fighting the guilty verdict, but changed his mind because he wanted to obtain a “Good Guy letter” from the NYPD — allowing those who retire or leave the department to carry a concealed firearm.

The documentation, which is almost always given to retiring full-duty cops, is a certificate signifying that the officer is “of good character” and competent to continue carrying a gun, despite now being a civilian.

As a result of his resignation, Haste — who was vested in the NYPD pension program — will not be granted his “Good Guy letter,” sources said.

He also won’t be eligible to receive his reduced pension until after the 20th anniversary of his appointment to the police department.

“Every step of the way, the mayor and NYPD have dragged their heels and have refused to hold officers accountable for murdering my son,” she seethed in a statement. “How is my youngest son supposed to trust and believe in cops when he saw they murdered his brother in front of him and there is zero accountability?”

Mayor de Blasio, on the other-hand, said he believed justice had been served.

“The NYPD disciplinary trial of Richard Haste ended with the right decision: termination,” the mayor said in a statement Sunday night. “Ramarley Graham was a son, a friend and, most importantly, a young man with his whole life left to live. Nothing can take away the profound pain left after his loss, but I hope the conclusion of this difficult process brings some measure of justice to those who loved him.”